Device for detecting a mechanical actuation of an input element by using digital technology, and method for processing and converting the digital input signal into commands for controlling a load

ABSTRACT

The aim of the invention is to develop a device for detecting and processing input pulses induced by a mechanical actuation of an input element, which is spring-suspended inside a plane and which can be actuated out of this plane both in a vertical direction as well as in a direction that is diagonal to the vertical at a specified angle, by transmission to a switching element that detects the actuating position. To this end, the inventive device is provided with a switch element ( 18, 15 ), which converts the series of motions, to which the input element ( 11 ) is subjected, into electrical digital signals, and with control electronics ( 16, 17 ). Said control electronics operate on the basis of a pattern recognition and convert the electrical signals, which are provided by the switch element ( 18, 15 ), into commands for subsequent loads. The switch element ( 18, 15 ) comprises a multitude of contact pairs of the contact matrix ( 15 ), whereby these contact pairs can be closed according to the position of the input element ( 11 ) based on an arbitrarily made selection.

The following invention describes an apparatus for the sensing of inputpulses caused by the mechanical activation of an input element, that areactivated during the operation of electronic devices by an operatingperson as well as a procedure to process the values of the input pulsesrelated to the measurable position of the activation.

The following techniques are known to in order to determine the positionof a switch element of electronic devices in the sense of a mechanicalmovement during activation:

-   -   so-called analogue joysticks of computer games contain two        potentiometers that are mechanically coupled to the tilt of the        joystick. Their electrical resistance corresponds to the x- and        y-values of the tilt.    -   Discs with holes can deliver digital signals when combined with        light barriers (opto couplers) to report the position of a        switch element. When the travel distance is sufficient, a high        resolution can be achieved.    -   Force sensors such as strain gauges, force sensing resistors        (FSR) or hall sensors deliver analog signals. Their values are        related to the force applied to the sensor. This is even        possible with a small travel distance.    -   Seesaw keys, often implemented as 2-way or 4-way cursor key pad,        measure one level in any of two or four directions, and        sometimes also the activation of the middle position. With        significant mechanical cost, special combination switches can        also determine a few more steps.

The solution with potentiometers is mechanically expensive, results in acertain weight and it is subject to vibration and shock. Thus,potentiometers are less suitable for mobile devices. Discs with holesand opto couplers are smaller, lighter and deliver a digital signal.They are also subject to mechanical vibration and also against dirt.

In contrast, force sensors can be built very small and mechanicallyrobust. However, they require a complex electronic controller with aninterpretation of sensed analog signals. This high cost prevents themass usage of force sensors with electronic devices.

Seesaw keys, on the other hand, are commonplace because they are small,light, robust and low-cost. However, they only offer 2 up to 5 switchpositions so they are not suitable for the operation of graphical userinterfaces.

A variable activatable input apparatus for cursor control on a PCdisplay is known from U.S. Pat. No. 5,815,139. This apparatus makes useof an input element that can be freely moved within one plane, and thatallows to register the positions of the tilted input element changed bymechanical force applied to flat sensor. The tilt and force applied tothe input element can be determined by measuring several variableresistances. During this process, analog measured values are deliveredthat can show inaccuracies due to temperature dependance. The processingof the measured values requires digitizing them, making a controllernecessary.

Several analog systems are known to transmit the movements forced to aninput element for mechanical devices. These are complicated tomanufacture and thus expensive. The mechanical devices can also becontrolled by electrical transmission systems, however there are nocomplementary low-cost apparatus to sense the mechanical activation ofan input element, so that it could detect any position of an inputelement during a mechanical activation during any movement phase.

The targets of the invention are to create an apparatus to sense inputpulses that are caused by a switch element that determines theactivation position of a mechanical activation of an input element, aswell as a small and robust construction, a low-cost design,easy-to-learn operation and a precise processing of the resulting inputpulses with electronic devices.

The invention's task is to develop an apparatus for sensing andprocessing input pulses that are caused by XXX 4/5.

The task is solved by the features described in the independent patentclaims.

According to the invention, a user interface element, e.g. a key or ajoystick is tilted against an elastic force, whereas an electricalconductive area at the underside of the user interface element touches acontact matrix at varying positions and thus closes electrical contacts.The closed contacts are related to the tilt of the user interfaceelement, where the closed contacts delive measurement values which areinterpreted by by an electronic controller, and where the procedureaccording to the invention determines the tilt, the direction ofactivation and the pressure force.

The invention will be demonstrated by means of an example. The figuresare as follows:

FIG. 1: a general structure of an apparatus according to the invention

FIG. 2: Possible operations of an input element of an apparatusaccording to the invention with an activation in vertical direction atvarious positions

FIG. 3: Possible operations of an input element of an apparatusaccording to the invention with an activation in vertical and thentilted directions

FIG. 4: Possible operations of an input element of an apparatusaccording to the invention with an activation in tilted direction

FIG. 5: an implementation of an input element according to theinvention, form factor “key”, position after vertical activation in thecenter of the input element with small force

FIG. 6: closed contacts according to FIG. 5

FIG. 7: an implementation of an input element according to theinvention, form factor “key”, position after vertical activation in thecenter of the input element with high force

FIG. 8: closed contacts according to FIG. 7

FIG. 9: an implementation of an input element according to theinvention, form factor “key”, position after a tilted activation at oneedge of the input element

FIG. 10: closed contacts according to FIG. 9

FIG. 11: closed contacts according to FIG. 9 with an alternating force

FIG. 12: an implementation of an input element according to theinvention, form factor “key”, position after a one-sided tiltedactivation at the outmost edge of the input element

FIG. 13: closed contacts according to FIG. 12

FIG. 14: an example for the design of the conductive paths, to determinethe degree of tilt within one axis (one-dimensional sensor)

FIG. 15: another example for the design of the conductive paths, todetermine the degree of tilt within one axis (one-dimensional sensor)

FIG. 16: a two-dimensional sensor with a disc-type input element, viewedfrom the top

FIG. 17: a two-dimensional sensor with a disc-type input element, viewedfrom the bottom

FIG. 18: a two-dimensional design of conductive paths

FIG. 19: another two-dimensional design of conductive paths

FIG. 20: another two-dimensional design of conductive paths

FIG. 21: an example for the closed contacts of a two-dimensional sensor

FIG. 22: another example for the closed contacts of a two-dimensionalsensor

FIG. 23: an implementation of an input element according to theinvention

FIG. 24: an implementation of an input element according to theinvention

FIG. 25: an implementation of an input element according to theinvention

FIG. 26: an implementation of an input element according to theinvention

FIG. 27: an implementation of an input element according to theinvention

FIG. 28: a portable computer with a touch-sensitive display

FIG. 29: a portable computer with a touch-sensitive display with anadd-on

FIG. 30: an add-on according to FIG. 29 in cross-section perspective

FIG. 31: a flowchart of the procedure according to the invention toevaluate the sensor signal

FIG. 32: a comparison of various sensor technologies

The apparatus according to the invention for sensing and processing ofinput pulses evoked by activation of input elements, and for theconversion of a digital input signal into commands for operatingelectronic devices consists of at least one input element 11 that isformed like a key and can be operated by a finger movement. Opposite itsactivation surface 10, on its underside 19, this input element featuresa calotte 12 consisting of a single material. The calotte 12 is formedlike a ball and is coated with an electrical conductive contact coating18 on a convex surface oriented towards the contact matrix 15, where theinput element 11 is mounted manouevrable against an elastic force 13within a casing not shown here. Underneath the input element 11 there isa base plate 14 that features a contact matrix 15 which is connected viaan interface with a scanning unit 16 for a real-time analysis of inputpulses, that is subsequently connected to a pattern recognition unit 17.

The input element 11 is operable with a finger movement on theactivation surface 10, alternatively in a vertical direction in the keycenter 22 like a pushbutton, or on its left edge 21 or its right edge23. This allows the contact coating 18 of the calotte 12 to closevarious contacts of a linear arrangement, i.e. alternating sequence ofthe contacts 142, 143, 144, 145 and 151 within the contact matrix 15depending on the position of the input element 11. The input element 11can be activated not only as described in vertical direction; if the keycenter 22 is kept pressed in a vertical direction, the input element 11can be forced into a rolling movement 24 either in the right or leftdirection. Depending on the degree of the rolling movement of thecalotte 12, the contact matrix 15 connects different contacts;additionally the applied force plays a role for the contact connections.If the calotte 12 is made of a deformable material, a varying pressureof the finger applied to the input element 11 leads to a varying numberof contacts closed simultaneously within the contact matrix 15 throughthe contact coating 18 of the calotte 12. Alternatively, the inputelement may be used with a joystick movement 25. The possibilities ofcontact connections depending on the described modes of operation of theinput element 11 are shown in FIGS. 5 to 12; indicating a stronger forceon the input element 11 with a bolder arrow symbol.

The contact matrix 15 consists, as shown in FIGS. 14 and 15, of severalelectrical single contacts 142, 143, 144, 145 and 151 in a contact row,which are mounted on a base plate 14. The contacts are activated by thecalotte 12 with its contact coating 18, which can optionally consist ofa deformable material that ensures a pressure-dependent number ofseveral contact closings. The calotte consisting of a deformablematerial may alternatively not be equipped with a contact coating 18 butconsist of a electrically conductive material; this is another aspect ofthe invention. The activation surface of the input element 11 can adoptany geometrical shape of a flat surface. In practice, two specific formshave evolved, a rectangular and a circular shape. The basic shape of thecalotte 12 depends on the selected shape of the activation surface 10.Other than the line-sequence arrangement of contacts in the contactmatrix 15, another aspect of the invention allows to adapt the form ofthe contact matrix 15 to the activation surface 10. This allows tooperate the input elelement 11 like an analog joystick, where the user'smovements of the input element 11 are detected.

The switch contacts of the contact matrix 15 are scanned by a scanningunit 16, as known from conventional keyboards. With the sensor designedaccording to the invention, however, the number of switch contacts ismuch higher. Depending on the tilt of the input element 11, differentcontacts on the contact matrix 15 are closed, as the convex underside 19of the calotte 12 of the input element 11 is rolled on the contactmatrix 15.

The plurality of switch contacts of the sensor lead to ambigous switchconditions, that cannot be interpreted by conventional circuitry. Aninnovative pattern recognition scheme as implemented by the procedureaccording to the invention interprets the switch conditions and assignsa tilt position and the orientation of the input element 11 to them andoptionally the applied force.

In its simplest form, the sensor consists of only two switches, whichcan be associated with four switch conditions (off, left, center,right), the center condition being reached when both contacts are closedat the same time. If more switches are available, a much higherresolution can be achieved; and with redundant contacts the reliabilitycan also be improved.

Depending on the implementation of the sensor, the movement resp. thetilt of the input element 11 can be determined either on one axis or ontwo axis. This requires a one-dimensional resp. two-dimensional contactarray. Additionally it is possible to conclude the applied force fromthe deformation of a soft calotte 12 and the resulting number of closedcontacts. The input element 11 with a convex calotte 12 at its underside19 is held in a center position against the base plate 14 by an elasticforce 13. If the input element 11 is pressed into the direction of thebase plate 14 with one or more fingers, then the calotte 12 ensureselectrical connections at certain positions of the contact matrix 15. Inthis context, the input element 11 is manouevrable downwards andtiltable.

The invention can be used in connection with a graphical user interfacewith various usages. Depending on the situation, different applicationscan be offered on the display. It is possible to implement parametersettings, menu navigation, key input and mouse pointer control withidentical hardware.

While ordinary keys only differentiate between a passive state and a keyactivation, the invention allows to register the details of operationthrough connections of the contact matrix 15 in so much detail, that thetilt of the input element 11 allows to conclude the position of one ormore finger on the input element 11.

FIG. 2 shows which typical user interface actions cause the tilt of aflat input element 11 that is similar to keys. The simplest case is thatthe input element 11 is activated at its left edge 21, at its center 22or at the right edge 23, with an ordinary brief press on the inputelement 11. The apparatus according to the invention does not justreceive an ordinary signal for the activated key, but also aninformation on which position the key has been activated. This allowsthe invention for example to distinguish between alternative keyassignments within an single keypress.

FIG. 3 illustrates the case when a key is pressed in its key center 22and held in that position. Even in the held-down state it is stillpossible to manipulate the input element 11 with the finger, so that thetilt of this key changes into the direction 24. From this user interfaceaction, the apparatus according to the invention does not just receive asingal for a continously held key, but also an up-to-date informationabout the specific tilt of the input element 11. This allows to activateand control a cursor movement with the invention.

FIG. 4 shows an application where a permanently resting input element 11can be moved like a joystick etc. The element bounces back into thecenter position when released.

FIGS. 5, 7, 9 and 12 show cross-sections of four different states of aninput element 11 according to the invention. FIGS. 6, 8, 10, 11, and 13show the corresponding contact matrix as a pattern resulting from eachactivation. In these figures, open contacts are indicated with a whiterectangle and closed contacts are indicated with a black rectangle.

FIG. 5 shows an input element 11 that has been normally activated in thecenter. The contact medium on the underside of the input element touchesthe conducting paths of the contact matrix 15 in the center accordingly,as indicated on FIG. 6 with two black rectangles.

On FIG. 7, the same input element 11 has been pressed slightly harder.Now the soft underside of the input element is deformed, i.e. thecalotte 12 (e.g. a pill made from electrically conductive rubber),resulting in contact between many points of the contact matrix 15, and asignal is generated with four little boxes. The difference between FIG.5 and FIG. 7 means that the construction according to the invention iscapable of measuring the force applied to the input element 11; althoughthis is only done indirectly through the deformation of the contactmedium of the calotte 12.

FIG. 9 displays the input element 11 activated at the left edge 21. Thiscould result in contacts of the contact matrix 15 as shown in FIG. 10and a corresponding signal. However, considering the huge number ofcontacts in the contact matrix 15 it is possible that single contactsfail in exceptional cases as illustrated on FIG. 11. The procedure tosense and process input pulses evoked by mechanical activation of inputelements according to the invention leads to useful results even in sucha case. This is because the electronic controller of the patternrecognition unit 17 determines the center of the closed contacts interms of the mathematical average of the position. This means that evenin this case a reflection of the tilt of the input element 11 comes as aresult.

FIG. 12 shows the input element 11 activated on the extreme right edge23, accordingly the contacts 63 are closed and the signals appear at theright side of the contact matrix as indicated on FIG. 13.

The procedure according to the invention allows to either determine thetilt of an input element along a single axis as shown on FIG. 5 to FIG.13, or alternatively the tilt of the input element 11 in arbitrarydirections can be registered. This depends only on the convex undersideof the input element 11 (longish or circular) and the contact matrix 15(strip-like or more like a square).

In order to measure on a single axis, a contact matrix as shown on FIG.14 or FIG. 15 is sufficient. The underside of the input element 11 mustlie down on these contacts when mechanical force in the range between 20and 500 grams is applied. Depending on the tilt of the input element 11,different contacts of the contact matrix 15 are closed. On FIGS. 14 and15 the potential resting area of the calotte 12 that is moved with theinput element 11 appears as a screened rectangle 141.

On FIG. 14, six conducting paths with contacts lead to the top andanother six lead to the bottom, the calotte 12 is capable of connectingthem. Such a contact matrix could therefore differentiate approximatelysix activation angles; to be precise, even more as intermediate valuescan be recognized through the combination of multiple contacts. Thecontact matrix 15 shown in FIG. 15 even allows to distinguish betweeneight activation angles with a lower count of conducting paths, asseveral conducting paths have been combined.

In its simplest case, a contact matrix 15 for a procedure according tothe invention could get along with three conductive paths: left side,right side and the electrical antithesis. This would result in onlythree activation angles (only left side or both or only right side).This would be a very inaccurate measurement, that could still be usefuldepending on the application.

FIG. 16. shows an input element 11 shaped like a disc, that can,originating from a home position in the center 161, be moved into anydirection by pressing the edge 162. FIG. 16 shows an example of an upperside of such an input element 11, while FIG. 17 shows the underside witha large circular calotte 12 in its center.

This shape of a calotte 12 could encounter grid-like conductive pathsequipped with contacts, for example, as shown on FIG. 18. With a largenumber of contact points, the conductive paths must be placed in twoelectrically separate layers. The right side of FIG. 18 shows anenlarged detail of the conductive paths, the vertical conductive pathplaced underneath and electrically separate from from the horizontalconductive path. FIG. 19 and FIG. 20 show further examples of suchconductive path layouts, where FIG. 20 requires only a singel layer ofconductive paths.

The electronic scanning unit 16 shown on FIG. 1 determines whichconnections are closed and derives from it a bit pattern that includesall possible contacts. Scanning the conductive paths is similar to thescanning of an ordinary PC keyboard. The different contact combinationsare subsequently supplied with signals and on the other side the levelsignals whether there is an electrical connection in the specific row orcolumn.

FIG. 21 and FIG. 22 show examples of such bit patterns derived byscanning. FIG. 21 shows the result of a medium force in the upper leftarea. The single light contact point within all the black spotsindicates a possible defect of a single contact point: Considering thelarge number of contact points and the possible rapid movement of thecontrol element, a perfect contact is impossible and not even necessary.The pattern recognition unit 17 shown in FIG. 1 calculates the averageof the registered conductive paths automatically. With FIG. 22, thelower count of contacts clearly indicates that the applied force on thecontrol element is lower than in the situation of FIG. 21.

The procedure to sense and process input pulses according to theinvention can be adapted to different shapes of input elements, as shownon FIG. 23 to FIG. 27. The input element 11 is mounted flexible in a waythat it can be pressed downwards and to the sides, but returns to itsoriginal position whenever it is released.

The input element 11 can be designed in a shape that resembleswell-known keys from pocket calculators, mobile phones etc. (FIG. 23 andFIG. 24). The calotte 12 serving as a contact medium (shown black inthese figures) however has a special curvature, that closes differentsingle or multiple contacts of the conductive paths depending on thetilt. In its simplest form, only two contacts can be closed that areestablished with three conductive paths. This allows to distinguishthree separate activation angles apart from the passive state. Thecalotte 12 is accordingly flat in its center and bevelled to the edge,to allow three positions with a specific activation angle for each.

This most basic implementation of the invention differs from knownseesaw keys in that way, that with the input elements according to theinvention either one, the other or both contacts may be closed (twosignals, three conditions), whereas with ordinary seesaw keys only asingle contact may be closed at a time (two signals, two conditions).

Besides, the input elements according to the invention exhibit none oronly a single tactile threshold. Even when due to low count ofconductive paths no individual tactile thresholds can be felt with theelastic force 13 of FIG. 1, it is still possible that certain edges 234;235 of the calotte 12 can be felt during a movement of the input element11 in held-down state according to FIG. 3.

With known seesaw keys however, every position requires a separatetactile threshold, because otherwise no unambigeous activation would bepossible. This means that the mechanical construction of known seesawkeys is complex, as the transition between the combined keys means anunstable connection. With the invention, however, the transitions andmultiple contacts pose no problem; in the contrary they are utilized todetermine the tilt of the input element 11. With an input element 11with a larger number of contacts (FIG. 24) the calotte 24 is roundedlike a cutout from a globe. The diameter of this fictional globe shouldapproximate the size of a human hand, as the input elements 11 aretilted with the hand.

A group of input elements 11 in the shape of keys according to FIG. 23and FIG. 24 can be produced like keyboards of common electronic devicesfrom a silicon rubber mat, that integrates the upper side of the inputelement 11, the elastic force at its edges and the fixing in a singleflexible component.

This allows a cost-effective production and allows the combination withordinary keys. According to FIG. 23 and FIG. 24, the contact medium canbe implemented as a carbon pill resp. made from electrically conductiverubber; these materials are widely known and used for keyboards.

Alternatively, a polyester dome foil can be mounted between the inputelement and the conductive paths, which fulfills the functions of theelastic force and with a conductive coating on its underside such ascarbon, metal etc. fulfills the function of the contact medium (FIG.25). Such input elements shaped like key domes can alternatively bebuilt completely from metal and are usable for a construction accordingto the invention, as long as the metal dome is soft enough to ensurecontacts according to the tilt.

A joystick on the basis of the same materials as FIG. 23 and FIG. 24 isshown FIG. 26. Such a design is cheap to produce and easy to combinewith keyboards.

At last it is possible to mount an input element detachable on a touchscreen as shown on FIG. 27. Touchscreens typically register a mechanicalactivation on a single spot of a display. The input element according tothe invention creates exactly such a pressure concentrated on a singlespot, where the touch position depends on the tilt. The grey shown baseplate 14 covers the touch screen and protects it from mechanicalpressure; at well-defined notches underneath the input elements anyinput element can however reach the touchscreen and activate it atdifferent coordinates depending on the tilt.

As a permanent construction it would be unreasonable to create such acombination, as a touch screen costs much more than a contact medium inthe form of a calotte together with conductive paths. However, as analternate input device this solution might be useful, e.g. as a keyboardthat could be mounted on a palm computer with tilting keys offeringmultiple key assignments, or as an optional mountable joystick for gamecontrol.

Palm computer and smart phones feature a casing 281 (FIG. 28) containinga large touch-sensitive display 271 as an input device (FIG. 28). Such atouchscreen is suitable for operating a graphical user interface with apen or with a finger directly on the display 271. At the same time, atouchscreen is less suitable for games (a joystick would be preferablefor these) and also less suitable for data entry (keys would bepreferable for input).

The invention allows to equip such a touchscreen device with additionalinput elements 11 within a very small space. To this end, the base plate14 of a unit according to the invention (FIG. 29) with input elements 11(FIG. 29) is mounted from the top or the side of the casing 281 (FIG.29), in a turn-over or clip manner, so that a part (max. 50%) of thetouchscreen, i.e. the display 271 (FIG. 29) is covered. The rest of thedisplay is still available for software displays.

The touchscreen surface 271 can be touched mechanically underneath thebase plate 14 by single input elements 11, if these are activated (FIG.30). The base plate 14 could for example be clipped to the sides of thecasing 281 (FIG. 30).

The electrical contacts that are closed through the activation of theinput elements 11 through the contact medium, the calotte 12, aresubsequently scanned by a electronic component, the scanning unit 16.This scanning is a well-known procedure, that is in use with almostevery keyboard of an electronic device, so there is no need to describeit in detail here. Existing devices make use e.g. of a contact matrix of8×8 conductive paths to scan a keyboard with up to 64 keys; theinvention uses a similar contact matrix for of a single input element11. The contacts are scanned just like keyboards with changing pulses ina rate between 5 and 50 scans per second.

The result of the scanning creates a bit pattern that is transmittedfrom the scanning unit 16 to a micro controller with software, thepattern recognition unit 17 for evaluation (FIG. 1). After every scancycle, a yes/no information is transmitted for every conductive pathwhich indicates whether the specific contact is closed (i.e. touched bythe contact medium) or open. This bit pattern allows the software tocalculate the position (resp. the tilt) as well as the applied pressureof the activation, if required.

The number of conductive paths can be varied depending on theapplication. More paths allow a higher precision of the tiltmeasurement, but require higher cost. In practice, between three andtwenty conductive paths will be reasonable for a one-axis measurement(as seen on FIG. 14 and FIG. 15) and with a measurement into alldirections, between six and a few hundred contact points.

The steps are listed in detail on FIG. 31. After the start, all inputelements are checked for activation at step 312. It is possible toevaluate a single element only or alternatively it is possible tocombine multiple input elements and evaluate them with one electroniccircuit. Step 312 ensures, that the following calculation are based onthe activated element and it is repeated (313), until an activation isdetected.

After this, the conductive paths of the activated element are analysed314. The bit pattern of the contacts allows to conclude the activationangle, i.e. the tilt of the element 315 by calculating the average ofthe positions. For instance, if there are ten conductive paths in oneaxis with an input element 11 and the paths 2, 3 and 5 are connected,then step 315 will make the following calculation: (2+3+5)/3=rounded3.33. Normally, all conductive paths are placed in a regular interval,and the calotte 12 will react to a changed angle with a proportionalchange of the contact position. In such a case, the average of thecontact positions directly resembles the tilt. For special applications,the conductive paths could also be placed in irregular intervals or thecontact medium calotte 12 can be especially flat or steep. In thesecases, the controller must determine the tilt with a table or specificformula that reflects the mechanical characteristics.

Step 316 (FIG. 31) determines the applied force, if this is relevant forthe application. In order to achieve this, the number of closed contactsis simply counted. A stronger pressure leads to a stronger deformationof the contact medium (calotte 12) and thus to a larger number ofcontacts.

This kind of force measurement is inaccurate and will in most cases onlyallow to distinguish between three and eight levels of pressure. Theexact conditions depend on the hardness and the form of the contactmedium (calotte). If a higher precision of force measurement isrequired, this can be achieved with a higher number of conductive paths,a softer contact medium (calotte) and a more accurate formula to reflectthe mechanical characteristics of the contact material (calotte).

At step 317, the result of the calculation are delivered to theoperating system (OS), where they may be used to control a cursor, for agame control or for data input. If the input element is activatedcontinously, the steps 313 to 317 are repeatedly passed, i.e. a possiblychanged activation position or force is permanently evaluated.

The sensor according to the invention constitutes a significantly morecompact sensor than potentiometers or discs with holes can offer inorder to determine the tilt of input elements. Therefore, it can easilybe integrated into mobile electronic devices just like known forcesensors and seesaw keys. The different properties of known technologiesin comparison with the invention are shown in the table of FIG. 32.

Force sensors make use of FSR (Force sensing resistors), strain gaugesor hall sensors as a basis for measurement. By contrast, the known keyssimply close an electric contact. The invention integrates a pluralityof electrical switches into a single mechanical input element.

Force sensors are used for example to operate of the mouse pointer ofnotebook computers, by mounting a small joystick between the keys(TrackPoint). A sensor underneath the TrackPoint measures the lateralforce that a person applies to it. A mechanical tactile threshold,similar to a key function, that would precede an activation is notprovided. However, there are versions of TrackPoint controls that allowan activation depending on a higher pressure like a mouse key function.Normal keys only react to an activation from the top, i.e. force applieddownwards. With the invention however, it is possible to register thetilt of an input element with a scalable resolution and at the same timethe function of several keys in a single input element is integrated.But this key function can be dropped depending on the application, sothat the invention can be used solely for cursor control. A tactilethreshold as with normal keys is possible with the invention, but couldbe dropped as well.

Typical force sensors allow to control a with a variable speed. This isalso possible with the invention, while ordinary keys do not offer sucha function. Force sensors have this capability because they can measureseveral levels of pressure, the resolution resulting from the sensorhardware. The established force sensors, especially strain gauges, offera high resolution of over one hundred steps. This makes them adequatefor controlling the mouse pointer of a notebook computer. With smallerelectronic devices, this precision is actually a disadvantage because itis not required and increases cost.

Keys do not allow a variable activation and therefore they are notcapable of analog control. The invention, however, is scalable in theway that depending on the requirements a higher or lower number ofconductive paths can be applied. At the same time, the input elementitself can be kept unchanged.

With force sensors, there is a definite relationship between the analoginput signal and the result of the required controller circuitry foranalog-digital conversion. With switches, there are only twoalternatives, open or closed. The invention, however, does evaluatedigital signals of the conductive paths, but it requires a patternrecognition procedure in order to calculate a position and if necessarythe force from a number of parallel activated switches.

If the tilt of the input element is evaluated on two axis, then theanalog signals of multiple force sensors can be interpolated todetermine the tilt direction. For example, if a sensor in a northdirection is activated as strong as a sensor in west direction, then itcan be concluded that the control element is tilted towards north-west.This is a well-known technology. The precision of analog force sensorsallows to differentiate more than one hundred segments of a circle.

Ordinary switches can differentiate as many directions as there areswitches, i.e. normally two or four. However, the invention allows todifferentiate between many more circle segments, depending on the numberof conductive paths, but less than with force sensors. For compactelectronic devices, this is fully acceptable.

Force sensors and the corresponding analog evaluation electroniccircuits are more or less temperature-sensitive; aging of components,production tolerances or lack of calibration can also lead toinaccuracies. Switches and the invention are not affected by thisproblem at all.

The solution according to the invention is much more reasonably priced,it is more robust and more compact than traditional potentiometers andcode switches. The invention goes far beyond traditional key functionsand is thus practical for the operation of powerful software userinterfaces with many functions. The resolution of the measurement islower than with high-grade force sensors. On the other side, the fullydigital evaluation and the almost perfect stability still guarantee aprecision that is comparable to force sensors.

The digital interface and the form factor that can be manufacturedautomatically as a component of keyboards allows to produce theinvention a level of scale cheaper than force sensors. The effort andthe resulting expenses are only slightly higher than traditionalkeyboards.

The scalable precision and the various constructions allow to adapt theinvention to almost any requirements; notably it offers both functionsfor cursor control as well as functions for data entry in keyboardstyle.

The measurement of the tilt of input elements for mobile electronicdevices requires sensors to control cursors and to operate the powerfulsoftware of current electronic devices, where the demands for the cursorpositioning are lower for a mobile device with a smaller screen thanwith a huge display.

Such sensors must be small, light, robust and easily and automaticallyproducable. It is an advantage if the sensors consists of very fewcomponents and can be integrated into keyboards. The solution describedby this invention fulfils these requirements.

LIST OF TERMS

-   10 user interface-   11 input element-   12 calotte-   13 elastic force-   14 base plate-   15 contact matrix-   16 scanning unit-   17 pattern recognition unit-   18 contact coating-   19 underside-   21 left edge-   22 center-   23 right edge-   24 Key with user interface action press and hold-   25 joystick movement-   62, 63 closed contact-   111 open contact-   141 screened rectangle-   142-145 contact-   161 center-   162 edge-   181, 182 conductive path-   211, 212, 231 average-   232 contact-   234, 235 edge-   236 casing-   251 flexible foil-   252 convex curvature-   253 electrically conductive coating-   254 case-   261 case-   271 display-   273 notch-   281 case-   311-315 step of algorithm

1. Device for detecting a mechanical actuation of an input element, thatis spring-suspended in one plane and is from this level actuatable bothin a vertical direction as well as in a direction that is diagonal tothe vertical at a specified angle to the vertical axis, comprising aswitch element (18; 15) converting the motions subjected onto the inputelement (11) into electrical, digital signals, and a control module (16;17) working on the basis of pattern recognition that translates theelectrical signals supplied from the switch element (18; 15) areprovided, wherein the switch element (18; 15) exhibits a multitude ofcontact pairs (142; 143; 143; 145; 151) of the contact matrix (15) thatcan be closed arbitrarily depending on the position of the input element(11).
 2. Device according to claim 1, wherein the switch element (12;15) consists of a base plate (14) placed underneath the input element(11) that exhibits a contact matrix (15) equipped with contacts (142;143; 144; 145; 151) and the input element (11) exhibits a calotte (12)on its underside (19) that exhibits an electrically conductive contactcoating (18) on its convex surfaces opposite to the underside (19). 3.Device according to claim 1, wherein the calotte (12) consists of adeformable material, mainly an elastomer.
 4. Device according to claim1, wherein the calotte (12) exhibits a flat area in its center with asurface stretching parallel to the underside (19) of the input element(11) and a bevel at its edges.
 5. Device according to claim 1, whereinthe contact matrix (15) exhibits a multitude of contacts (142; 143; 144;145; 151) along one axis.
 6. Device according to claim 1, wherein thecontact matrix exhibits a two-dimensional contact allocation.
 7. Deviceaccording to claim 1, wherein the calotte (12) exhibits a profile of apolygone shape with no more than ten edges (234; 235) that correspondsto the underside (19) of the input element (11).
 8. Device according toclaim 1, wherein the calotte (12) exhibits a circular shape.
 9. Deviceaccording to claim 1, wherein the contacts (142; 143; 144; 145; 151) ofthe contact matrix (15) are arranged in pairs of an alternatingsequence.
 10. Device according to claim 1, wherein the contacts (142;143; 144; 145; 151) of the contact matrix (15) are arranged coaxial toeach other in an alternating sequence.
 11. Device according to claim 1,wherein the contacts (142; 143; 144; 145; 151) of the contact matrix(15) are arranged in a cross-over sequence.
 12. Device according toclaim 1, wherein a flexible foil (251) is provided underneath the inputelement (11) between the calotte (12) and the contact matrix (15) with aconvex curvature (252) that is flexibly manouevrable into the directionof the input element (11) and is equipped with an electrical conductivecoating (253) at its underside in the area of the contact matrix (15).13. Device according to claim 1, wherein the input element (11) isshaped as a joystick and flexibly mounted underneath a case cover (261),the calotte (12) having a convex shape.
 14. Device according to claim 1,wherein the input element (11) is mounted flexibly opposite to the baseplate (14) within the casing (231) and is fixed to the base plate (14),the base plate (14) exhibiting a notch (273) through which the calotte(12) can actuate a touch screen (272).
 15. Device according to claim 1,wherein the input element (11) and the casing (231) exhibiting flexiblecharacteristics constitute a constructive unit.
 16. Device according toclaim 1, wherein the base plate (14) is equipped with a softwarecontrolled electro magnet, delivering a tactile feedback to theactuation status of the input element (11).
 17. Device according toclaim 1, wherein an inte-grated circuit is provided underneath the inputelement (11), i.e. on the base plate (14) that exhibits a multitude ofelectrodes performing the function of contacts, the integrated circuitbeing equipped with two power supply contacts, an input datatransmission line for configuration and three output data transmissionlines for output data of x, y and z values of the corresponding spatialaxes.
 18. Device according to claim 1, wherein the base plate (14) lieson a display (271) with an integrated touch screen (272) and attached toit in a way that is undoable without any tools, so that the convexcalotte (12) activates the touch screen (272) through a notch (273) inthe base plate (14) whenever the input element (11) is activated, sothat the touch screen (272) registers a specific position on the touchscreen area depending on the actuation angle of the input element (11)because of the mechanical actuation by the calotte (12), and thisposition is transmitted for further processing, leading to a differentcontent on the display (271) depending on the position.
 19. Method for adevice according to claim 1, wherein a scanning unit (16) checks therows and columns of a contact matrix (15) for an electrical connectionin a rapid sequence approx. 50 times per second and an arbitrarycombination of contacts of the contact matrix (15) may be connected andthe scanning unit (16) generates a bit pattern from these checks that istransmitted to a pattern recognition unit (17) for further processing.20. Method for a device according to claim 19, wherein a patternrecognition unit (17) interprets a bit pattern received from thescanning unit (16), the bits representing closed contacts (62) of acontact matrix (15), in a way that an arithmetical average is derivedfrom the spatial position (63) of the closed contacts and the tilt ofthe input element (11) along an axis is derived from this result. 21.Method for a device according to claim 18, wherein a pattern recognitionunit (17) interprets a bit pattern received from the scanning unit (16),the bits representing closed contacts (62) of a contact matrix (15), ina way where the number of closed contacts is summed up to derive theflattening of a calotte (12) during the activation of the input element(11) and the applied pressure of the input element (11) is derived fromthis result.
 22. Method for a device according to claim 18, wherein apattern recognition unit (17) interprets a bit pattern received from thescanning unit (16), the bits representing closed contacts (62) of acontact matrix (15), in a way that two arithmetical averages (211; 212)are derived from the spatial positions (63) of the closed contacts andthe tilt of the input element (11) along two axes is derived from thisresult.
 23. Method according to claim 19, wherein the calotte (12) of around input element (11) closes a multitude of contacts on a contactmatrix (15), that are arranged in a two-dimensional contact matrix, thecontroller deriving the tilt from the position of the closed contacts.24. Method according to claim 18, wherein the calotte (12) of an inputelement (11) closes up to two contacts on a contact matrix (15), so thata lateral actuation closes a single contact and an actuation in thecenter closes two contacts.
 25. Method according to claim 18, wherein tomeasure the activation of input elements (11) of electronic devices, theinput element (I 1) formed like a key or a joystick can be tiltedagainst an elastic force by an operating person, so that an electricallyconductive, curved area on the underside (19) of the input element (11)touches a contact matrix (15) at various positions and thus closes oneor more electrical contacts, that are evaluated by a control moduleconsisting of a scanning unit (16) and a pattern recognition module(17), the tilt and the direction of the activation of the input element(11) being derived from the position of the closed contacts.
 26. Methodaccording to claim 18, wherein the applied pressure is derived from thenumber of closed contacts, the number of closed contacts beingdetermined by a flattening of the contact medium calotte (12) on thecontact matrix (15) as a result of the force applied to the inputelement (11).